1. Field of the Invention
The present invention relates to a signal processor for processing signals read from an information recording medium such as a CD (Compact Disk), DVD (Digital Versatile Disk), and MD (Mini Disk).
2. Description of the Related Art
There has been developed a digital playback system capable of audio effects control in real time through tempo (BPM: Beats Per Minute) change applied to playback audio of audio data read from an information recording medium such as a CD. Such a digital playback system allows users' real-time processing applied to playback audio through operation of dials and buttons, e.g., tempo acceleration, tempo deceleration, playback pause, and backward playback. With such processing, audio effects can be originally improvised by the user. Conventionally, with an analog record player, tempo change of playback audio has been done by varying the movement speed of a phonograph needle that traces grooves formed on an analog record for audio recording. During playback of the analog record, the user forcibly rotates a turntable carrying thereon the analog record with a speed different from a normal rotation speed. Such tempo change conventionally done by the analog record player is now done with the above-described digital playback system using CDs and DVDs recording digital information.
The conventional technology relevant to the above digital playback system is found in Patent Document 1 (Japanese Patent Kokai No. 2003-132634), for example.
While, in recent years, optical disks storing video information such as movies have been commonly on the market, no system is yet available for exercising real-time control over video effects during video playback from such optical disks.
The digital playback system found in Patent Document 1 and others can store a plurality of playback positions for audio data recorded on CDs and others. Such stored playback positions are called with any desired timing for audio playback therefrom to produce any desired audio effects. The issue is that, since these playback positions are numerically expressed by playback time and others, such a numerical expression is hardly associated with actual playback audio. Thus, to check the audio in the neighborhood of the playback positions, user needs to play back and listen to the audio from the playback position. Additionally, when many playback positions are stored, user is likely to choose the wrong playback position.